Heat shielding material and method for manufacturing the same

ABSTRACT

A heat shielding material and method for manufacturing thereof is provided. The method for manufacturing the heat shielding material, includes: providing a tungsten oxide precursor solution containing a group VIIIB metal element; drying the tungsten oxide precursor solution to form a dried tungsten oxide precursor; and subjecting the dried tungsten oxide precursor to a reducing gas at a temperature of 100° C. to  500 ° C. to form a composite tungsten oxide. The heat shielding material includes composite tungsten oxide doped with a group IA or IIA metal and halogen, represented by M x WO y  or M x WO y A z , wherein M refers to at least one of a group IA or IIA metal, W refers to tungsten, O refers to oxygen, and A refers to a halogen element. The heat shielding material also includes a group VIIIB metal element.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of pending U.S. patent application Ser.No. 13/040,780, filed on Mar. 4, 2011 and entitled “Heat shieldingmaterial and method for manufacturing the same”, which claims priorityof Taiwan Patent Application No. 99142537, filed on Dec. 7, 2010 andTaiwan Patent Application No. 100104518, filed on Feb. 11, 2011, theentirety of which is incorporated by reference herein.

TECHNICAL FIELD

The technical field relates to a heat shielding material and a methodfor manufacturing the same, and in particular relates to an infrared(IR) reflection film and a method for manufacturing the same.

BACKGROUND

Glass is generally heated at a high temperature of about 680° C. to 710°C. (in air) to strengthen an intensity thereof. Although a protectivelayer may be coated onto a heat shielding film of the glass to preventoxidization thereof, the extra step increases process complexity.

Alternatively, a heat shielding material may be coated onto the glassafter the high temperature strengthening process so that the heatshielding performance of the glass does not deteriorate. Note that iftempered glass is subjected to a temperature higher than 300° C., straintherein would be released, thus causing the glass to lose its toughness.Tungsten oxide film is a well known heat shielding film with IRreflexivity. Tungsten oxide films are generally formed at a temperatureabove 500° C., and therefore, it is not suitable for tungsten oxidefilms to be incorporated into a tempered-glass manufacturing process.

A commercially available heat shielding glass is mainly a low radiationglass with single layer or double layer of silver, which is formed bysputtering silver, dielectric, and a protective film on the glass undera vacuum environment.

Therefore, the silver coating must be sealed between two pieces of glassfilled with inert gas to prevent oxidation. However, if the inert gasleaks, the heat shielding performance will be negated and replacement ofthe gas assembly will be required.

Accordingly, a low-cost, highly stable IR reflective film which can beprocessed by a lower temperature is required.

SUMMARY

An embodiment of the disclosure provides a method for manufacturing aheat shielding material, comprising: providing a tungsten oxideprecursor solution containing a group VIIIB metal element; drying thetungsten oxide precursor solution to form a dried tungsten oxideprecursor; and subjecting the dried tungsten oxide precursor to areducing gas at a temperature of 100° C. to 500° C. to form a compositetungsten oxide.

Another embodiment of the disclosure provides a heat shielding material,comprising: composite tungsten oxide doped with a group IA or IIA metal,represented by MxWOy, wherein M refers to at least one of a group IA orIIA metal, W refers to tungsten, O refers to oxygen, and 0<x≦1, and2.2≦y≦3; and a group VIIIB metal element.

Another embodiment of the disclosure provides a heat shielding material,comprising: composite tungsten oxide doped with a group IA or IIA metal,represented by MxWOyAz, wherein M refers to at least one of a group IAor IIA metal, W refers to tungsten, O refers to oxygen, and A refers toa halogen element, and 0<x≦1, 2.2≦y+z≦3, and 0<Z≦0.2; and a group VIIIBmetal element.

A detailed description is given in the following embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The present disclosure can be more fully understood by reading thesubsequent detailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 is a UV-VIS-IR spectrum of the tungsten oxide film with orwithout adding a group VIIIB metal catalyst during the manufacturingprocess in accordance with an embodiment of the disclosure.

FIG. 2 illustrates the IR reflection of the tungsten oxide film formedunder various reduction temperatures in accordance with an embodiment ofthe disclosure.

FIG. 3 illustrates the IR reflection of the tungsten oxide film formedunder various reduction time in accordance with an embodiment of thedisclosure.

FIG. 4 illustrates the IR reflection of the tungsten oxide film formedunder different reduction temperatures and different reduction times inaccordance with an embodiment of the disclosure.

FIGS. 5-6 illustrate the IR reflection of the tungsten oxide film afteradding different amounts of catalysts during the manufacturing processin accordance with an embodiment of the disclosure.

FIGS. 7-8 illustrate the IR reflection of the tungsten oxide film afteradding different catalysts during the manufacturing process inaccordance with an embodiment of the disclosure.

FIGS. 9-10 illustrates the XRD spectra of the tungsten oxide film withor without adding a group VIIIB metal catalyst during the manufacturingprocess in accordance with an embodiment of the disclosure.

FIG. 11 illustrates the XRD of the tungsten oxide film formed under lowreduction temperature in a best mode in accordance with an embodiment ofthe disclosure.

FIG. 12 illustrates the IR reflection of the composite tungsten oxidefilm after adding halogen salt during the manufacturing process inaccordance with an embodiment of the disclosure.

DETAILED DESCRIPTION

Below, exemplary embodiments will be described in detail with referenceto accompanying drawings so as to be easily realized by a person havingordinary knowledge in the art. The inventive concept may be embodied invarious forms without being limited to the exemplary embodiments setforth herein. Descriptions of well-known parts are omitted for clarity,and like reference numerals refer to like elements throughout.

In an embodiment of the present disclosure, a group VIIIB metal catalystis added to form a composite tungsten oxide film to reduce formationtemperature of the composite tungsten oxide, such that an IR reflectivecoating may be formed at a temperature of below about 500° C.Embodiments of manufacturing the composite tungsten oxide film aredescribed in detail below.

In an embodiment, the group VIIIB metal catalyst is first added to amixed solution of a tungsten oxide precursor and a IA or IIA metal saltto form a tungsten oxide precursor solution. The group VIIIB metalcatalyst described above may be added to the precursor solution in aform of metal, metal oxide, or metal salt. For example, the group VIIIBmetal catalyst may comprise Pt, PtO₂, H₂PtCl₆.H₂O, H₂PtCl₆.6H₂O, N₂O₆Pt,PtCl₄, C₄H₆O₄Pt, Ni, NiO, Ni₂CO₃, C₄H₆O₄Ni.4H₂O, NiCl₂, H₈N₂NiO₈S₂.6H₂O,NiCl₂.6H₂O, NiF₂, NiBr₂, NiCl₆.6H₂O, Rh, Rh₂O₃, RhCl₃.H₂O, N₃O₉Rh,C₄H₉O₆Rh, Pd, PdO, H₂O₂Pd, N₂O₆Pd, PdBr₂, C₄H₆O₄Pd, PdCl₂, or acombination thereof. The additional amount of the group VIIIB metalcatalyst may be between about 0.001 to 1 wt %.

The tungsten oxide precursor may comprise ammonium metatungstate,ammonium orthotungstate, ammonium paratungstate, alkali metal tungstate,tungstic acid, tungsten silicide, tungsten sulfide, tungstenoxychloride, tungsten alkoxide, tungsten hexachloride, tungstentetrachloride, tungsten bromide, tungsten fluoride, tungsten carbide,tungsten oxycarbide, or a combination thereof.

The group IA or IIA metal salt is represented by a formula of M_(p)N,wherein M is a group IA or IIA metal element comprising lithium (Li),sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), beryllium (Be),magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), or acombination thereof, and N is an anion or an anion group with negativevalence, and 0.5≦p≦12. The group IA or IIA metal salt comprises group IAor IIA metal carbonate, group IA or IIA metal hydrogen carbonate, groupIA or IIA metal nitrate, group IA or IIA metal nitrite, group IA or IIAmetal hydroxide, group IA or IIA metal halide, group IA or IIA metalsulfate, group IA or IIA metal sulfite, or a combination thereof. Amolar ratio of the tungsten oxide precursor and group IA or IIA metalsalt may be between 0.05 and 1, preferably between 0.2 and 0.8.

In one embodiment, the tungsten oxide precursor and group IA or IIAmetal salt may be added into distilled water and thoroughly mixed. Then,the pH value of the mixed solution is adjusted to over 7 and preferablyabout 9-12 by an organic base or an inorganic base. Then, the groupVIIIB metal catalyst is added into the mixed solution (alternatively,the catalyst may be added before the pH adjustment) to obtain thetungsten oxide precursor solution. The organic base may comprise organicamines such as dimethyl amine, trimethyl amine, piperidine, morpholino,triethyl amine, pyridine and so on. The inorganic base may compriseammonia, hydroxide of group IA or IIA metal, carbonate of group IA orIIA metal, bicarbonate of group IA or IIA metal, or the like. Forexample, sodium bicarbonate, potassium bicarbonate, lithium carbonate,sodium carbonate, potassium carbonate, lithium hydroxide, sodiumhydroxide, potassium hydroxide, barium hydroxide, or the like.

In another embodiment of the present disclosure, a heat shieldingmaterial doped with halogen may also be formed. In this case, in thepreparation steps of the tungsten oxide precursor solution describedabove, halogen salt may be added thereto. The halogen containingtungsten oxide precursor solution is then coated onto a substrate anddried to form a film. The additional amount of halogen salt may bebetween about 0.1 and 20 mol %, wherein being between 1 and 15 mol % ispreferred. The halogen salt described above is represented by a formulaof PA_(q), wherein A is a halogen element comprises fluorine (F),chlorine (Cl), bromine (Br), or iodine (I), and P is a cation or acation group with positive valence, and 1≦q≦12. The halogen salt maycomprise ammonium halide, alkylammonium salt, halocarbon, hydrogenhalide, tungsten halide, benzene halide, halogenated aromatic, or alkylhalide.

Then, the tungsten oxide precursor solution is coated onto a substrate.The coating procedure can be achieved by various wet coating techniquessuch as spin coating, casting, bar coating, blade coating, rollercoating, wire bar coating, dip coating, or the like. The substratedescribed above may comprise glass substrate, transparent resinsubstrate, or a combination thereof. In one embodiment of thedisclosure, the glass substrate may be tempered glass. In anotherembodiment of the disclosure, the transparent resin substrate maycomprise polyester, polyimide resin, acrylic resin, epoxy resin,silicone resin, phenoxy resin, urethane resin, urea resin, acrylonitrilebutadiene styrene (ABS) resin, polyvinyl butyral (PVB) resin, polyetherresin, florine-containing resin, polycarbonate, polystyrene, polyamide,starch, cellulose, a copolymer thereof, a mixture thereof, or the like.

After the coating step, the substrate is dried in an oven at atemperature of about 25 to 200° C. for about 0.5 to 30 minutes, thusforming a film with a pyrochlore structure which does not hinder IRreflective performance.

The dried film is placed in reducing gas for reduction reaction at atemperature of about 100 to 500° C., preferably about 250 to 500° C. Thereducing gas may be gas such as hydrogen, wherein the percentage ofhydrogen may be about 1 to 100% (vol). The reducing process proceeds forabout 10 to 480 minutes, preferably about 20 to 240 minutes. After thereduction, the pyrochlore structure of the film transforms into ahexagonal structure. An IR reflective and transparent film is thenformed. Usually, the higher the reduction temperature, the shorter thereaction time. In other words, the reaction time needs to be extended ifa lower reduction temperature is desired. Therefore, the reduction timeand temperature can be adjusted depending on the characteristics of thesubstrate or other processing needs. Therefore, the manufacturingprocess can be integrated into the present manufacturing process oftempered glass or other transparent substrates.

Since the conventional process of forming a composite tungsten oxidefilm requires a temperature of over about 500° C., the conventionalprocess is not appropriate to be used in the heat shielding coatingtreatment of a tempered glass which requires a low temperature process.However, in an embodiment of the disclosure, the group VIIIB metalcatalyst (such as Pt) is added to reduce the formation temperature ofthe composite tungsten oxide film, such that the tungsten oxide film maybe formed at a temperature of below about 300° C. Thus, applicability ofthe heat shielding film is increased; especially for tempered glasses.

Note that during the manufacturing process of the heat shieldingmaterial, the group VIIIB metal catalyst is added and not removed.Therefore, the composite tungsten oxide film of the disclosure ischaracterized by containing a certain amount of the group VIIIB metalcatalyst, wherein the amount is usually between about 0.001 and 1 wt %,such as about 0.1 to 0.6 wt %. A transparency of the heat shielding filmmay be about 20 to 85%.

In an embodiment of the disclosure, the step of coating the tungstenoxide precursor solution on the substrate may be omitted. That is, thetungsten oxide precursor solution may be directly oven dried andsubjected to a reducing gas for reduction. The reduction temperature maybe between about 100 and 500° C., wherein a temperature of about 250 to500° C. is preferred. Following, a composite tungsten oxide powdercontaining the group VIIIB metal element is thus formed. The powder maybe ground and dispersed into a medium such as a solvent or a resin toform nano-dispersion. Then, the nano-dispersion is coated onto glass ora transparent polymer substrate to form a transparent heat shieldingfilm.

A heat shielding material according to an embodiment of the disclosurecomprises composite tungsten oxide doped with a group IA or IIA metal,represented by formula (I):

M_(x)WO_(y),   (I)

wherein M refers to at least one of a group IA or IIA metal, W refers totungsten, O refers to oxygen, and 0<x≦1, and 2.2≦y≦3. Furthermore, agroup VIIIB metal element of the heat shielding material is about 0.001to 1 wt % of the composite tungsten oxide, preferably about 0.1 to 0.6wt %. The formed heat shielding material has good IR reflection at awavelength over about 780 nm. In particular, the IR reflection at about1400 to 2600 nm may be about 50 to 70%, or even above 70%.

Moreover, a heat shielding material according to another embodiment ofthe disclosure comprises composite tungsten oxide doped with a group IAor IIA metal and halogen, represented by formula (II):

M_(x)WO_(y)A_(z),   (II)

wherein M refers to at least one of a group IA or IIA metal, W refers totungsten, O refers to oxygen, A refers to a halogen element, and 0<x≦1,2.2≦y+z≦3, and 0<Z≦0.2. A group VIIIB metal element of the heatshielding material is about 0.001 to 1 wt % of the composite tungstenoxide, preferably about 0.1 to 0.6 wt %. The heat shielding materialdescribed above may be in the form of a powder or a film.

In view of the above, the disclosure provides a low-temperature processfor forming a heat shielding film and a heat shielding film formedthereby. The conventional heat shielding glass formed by vacuum coatingrequires a high cost and multilayered formations. In comparison, theheat shielding material of the disclosure requires only a single layeredcoating. Thus, the process is easier, and the cost is lower. Further,since the inert gas for preventing oxidation is not needed in thepresent disclosure, stability and durability of the glass can be higher.

In addition, compared to the composite tungsten oxide film without usingthe group VIIIB metal catalyst during a formation process thereof, thecomposite tungsten oxide film using the group VIIIB metal catalyst mayreduce the temperature of the reduction reaction. The traditionalcomposite tungsten oxide needs to be formed at a temperature of overabout 500° C., and can not be applied to manufacturing of a temperedglass. However, the composite tungsten oxide film of the disclosure maybe formed at a temperature of lower than about 500° C., or even lowerthan about 300° C., with superior IR reflection. Thus, the compositetungsten oxide film of the disclosure may be used in more applications.The composite tungsten oxide film of the disclosure has superior IRreflection at a wavelength higher than about 780 nm. In particular, at awavelength of about 1400 to 2600 nm, the IR reflection may reach about50 to 70%, or even above 70%.

COMPARATIVE EXAMPLE 1

5 g of ammonium metatungstate and 1.1 g of cesium carbonate was addedinto 40 mL of distilled water and thoroughly mixed. The pH value of themixture was adjusted to 12 by an NH₄OH aqueous solution, and a tungstenoxide precursor solution (without the group VIIIB metal catalyst) wasprovided. The tungsten oxide precursor solution was coated onto a glasssubstrate by dipping coating and then oven dried at a temperature of120° C. Finally, the dried substrate was subjected to 10% (vol) of H₂/Arat 400° C. for 60 minutes to form a composite tungsten oxide film. TheUltraviolet-Visible-Infrared (UV-VIS-IR) spectrum of the compositetungsten oxide film was measured by a SHIMADZU (UV-3600) for wavelengthsbetween 240 to 2600 nm with a Scan spacing of 5 nm.

EXAMPLE 1

5 g of ammonium metatungstate and 1.1 g of cesium carbonate was addedinto 40 mL of distilled water and thoroughly mixed. The pH value of themixture was adjusted to 12 by an NH₄OH aqueous solution. 0.4 wt % ofH₂PtCl₆.H₂O was added into the mixture to form a tungsten oxideprecursor solution. The tungsten oxide precursor solution was coatedonto a glass substrate by dipping coating and then oven dried at atemperature of 120° C. Finally, the dried substrate was subjected to 10%(vol) of H₂/Ar at 400° C. for 60 minutes to form a composite tungstenoxide film. A UV-VIS-IR spectrum of the composite tungsten oxide film isshown in FIG. 1.

FIG. 1 illustrates the IR reflection of the composite tungsten oxidefilms with or without the catalyst. As shown in FIG. 1, the IRreflection of the composite tungsten oxide film with Pt, the group VIIIBmetal catalyst, is much higher than the IR reflection of the compositetungsten oxide film without the catalyst. That is, adding the groupVIIIB metal catalyst can effectively improve the IR reflection of thecomposite tungsten oxide film, with good transparency.

EXAMPLE 2

5 g of ammonium metatungstate and 1.1 g of cesium carbonate was addedinto 40 mL of distilled water and thoroughly mixed. The pH value of themixture was adjusted to 12 by an NH₄OH aqueous solution. 0.4 wt % ofH₂PtCl₆.H₂O was added into the mixture to form a tungsten oxideprecursor solution. The tungsten oxide precursor solution was coatedonto a glass substrate by dipping coating and then oven dried at atemperature of 120° C. Finally, the dried substrate was subjected to 10%(vol) of H₂/Ar for 60 minutes to form a composite tungsten oxide film.The reduction temperature was 260° C., 300° C., 400° C., or 500° C.,respectively. The UV-VIS-IR spectrum of the composite tungsten oxidefilm is shown in FIG. 2.

FIG. 2 illustrates the IR reflection of the composite tungsten oxidefilms formed at different reduction temperatures. As shown in FIG. 2,the composite tungsten oxide films formed at different reductiontemperatures all have superior IR reflection.

EXAMPLE 3

5 g of ammonium metatungstate and 1.1 g of cesium carbonate was addedinto 40 mL of distilled water and thoroughly mixed. The pH value of themixture was adjusted to 12 by an NH₄OH aqueous solution. 0.4 wt % ofH₂PtCl₆.H₂O was added into the mixture to form a tungsten oxideprecursor solution. The tungsten oxide precursor solution was coatedonto a glass substrate by dipping coating and then oven dried at atemperature of 120° C. Finally, the dried substrate was subjected to 10%(vol) of H₂/Ar at 300° C. to form a composite tungsten oxide filmreacting at different reactions time. The variation of the IR reflectionof the tungsten oxide film formed with different reduction times duringthe forming process is shown in FIG. 3.

As shown in FIG. 3, the IR reflection of the tungsten oxide film canreach about 70% when the reduction reaction lasts for 60 minutes at atemperature of 300° C. Accordingly, adding the group VIIIB metalcatalyst can reduce the reduction temperature thereof and thereforeincrease applicability.

EXAMPLE 4

5 g of ammonium metatungstate and 1.1 g of cesium carbonate was addedinto 40 mL of distilled water and thoroughly mixed. The pH value of themixture was adjusted to 12 by an NH₄OH aqueous solution. 0.4 wt % ofH₂PtCl₆.H₂O was added into the mixture to form a tungsten oxideprecursor solution. The tungsten oxide precursor solution was coatedonto a glass substrate by dipping coating and then oven dried at atemperature of 120° C. Finally, the dried substrate was subjected to 10%(vol) of H₂/Ar to form a composite tungsten oxide film. The reductiontemperature was at 260° C., 300° C., 400° C., or 500° C., respectively,and the reaction time was 240 or 60 minutes. The UV-VIS-IR spectrum ofthe composite tungsten oxide film is shown in FIG. 4.

FIG. 4 illustrates the IR reflection of the composite tungsten oxidefilms formed at different reduction temperatures for different reductiontimes. When a lower reduction temperature was required, the IRreflection of the composite tungsten oxide film may be increased byhaving a longer reduction time. When the reduction temperature was high,a shorter reduction time can achieve a desired IR reflection. Therefore,the reduction time and temperature can be adjusted according toapplications.

EXAMPLE 5

5 g of ammonium metatungstate and 1.1 g of cesium carbonate was addedinto 40 mL of distilled water and thoroughly mixed. The pH value of themixture was adjusted to 12 by an NH₄OH aqueous solution. 0.4 wt % ofH₂PtCl₆.H₂O was added into the mixture to form a tungsten oxideprecursor solution. The tungsten oxide precursor solution was coatedonto a glass substrate by dipping coating and then oven dried at atemperature of 120° C. Finally, the dried substrate was subjected to 10%(vol) of H₂/Ar at 400° C. for 60 minutes to form a composite tungstenoxide film. A accelerated weathering testers (QUV) test chamber was usedto test the durability of the composite tungsten oxide film for exposureunder QUV for 150, 600, 1000, 2000 hrs. Then, a UV-VIS-IR was used.After continuous exposure in the QUV test chamber, the compositetungsten oxide film still had good transparency and IR reflection.

Therefore, the composite tungsten oxide film of the disclosure did nottend to oxidize as those conventional heat shielding glass with silvercoating. Forming a conventional heat shielding glass requires sealing ofa silver coating into the inert gas between two layers of glass toprevent the oxidation of the silver coating. Once the inert gas betweenthe two layers of glass leaks out, the glass no longer has the abilityof heat shielding. However, in this disclosure, a multilayered glass andthe inert gas is not required, and thus, the composite tungsten oxidefilm of the disclosure can have superior stability and durance.

EXAMPLE 6

5 g of ammonium metatungstate and 1.1 g of cesium carbonate was addedinto 40 mL of distilled water and thoroughly mixed. The pH value of themixture was adjusted to 12 by an NH₄OH aqueous solution. 0.1, 0.4, 0.8wt % of H₂PtCl₆.H₂O was added into the mixture respectively to form atungsten oxide precursor solution. The tungsten oxide precursor solutionwas coated onto a glass substrate by dipping coating and then oven driedat a temperature of 120° C. Finally, the dried substrate was subjectedto 10% (vol) of H₂/Ar at 400° C. for 60 minutes to form a compositetungsten oxide film. A UV-VIS-IR was used to examine the IR reflectionand transparency of the tungsten oxide film. As shown in FIG. 5 and FIG.6, only a small amount of the catalyst is required to achieve a desiredheat shielding ability.

EXAMPLE 7

5 g of ammonium metatungstate and 1.1 g of cesium carbonate was addedinto 40 mL of distilled water and thoroughly mixed. The pH value of themixture was adjusted to 12 by an NH₄OH aqueous solution. 0.4 wt % ofgroup VIIIB metal catalyst was added into the mixture to form a tungstenoxide precursor solution, wherein the group VIIIB metal catalyst wasH₂PtCl₆.H₂O, NiCl₆.6H₂O, RhCl₃.H₂O, or PdCl₂, respectively. The tungstenoxide precursor solution was coated onto a glass substrate by dippingcoating and then oven dried at a temperature of 120° C. Finally, thedried substrate was subjected to 10% (vol) of H₂/Ar at 400° C. for 60minutes to form a composite tungsten oxide film. A UV-VIS-IR was used toexamine the IR reflection and transparency of the formed tungsten oxidefilm. As shown in FIG. 7 and FIG. 8, adding different kinds of groupVIIIB metal catalysts during the manufacturing process can improve theIR reflection of the formed composite tungsten oxide film.

EXAMPLE 8

5 g of ammonium metatungstate and 1.1 g of cesium carbonate was addedinto 40 mL of distilled water and thoroughly mixed. The pH value of themixture was adjusted to 12 by an NH₄OH aqueous solution. 0.4 wt % ofH₂PtCl₆.H₂O was added into the mixture to form a tungsten oxideprecursor solution. The tungsten oxide precursor solution was coatedonto a glass substrate by dipping coating and then oven dried at atemperature of 120° C. Finally, the dried substrate was subjected to 10%(vol) of H₂/Ar for 20 minutes to form a composite tungsten oxide film.The reduction temperature was at 260° C., 300° C., 400° C., or 500° C.,respectively.

Meanwhile, the tungsten oxide precursor solution without H₂PtCl₆.H₂O wasalso prepared as a comparative example. The tungsten oxide precursorsolution formed without catalyst was coated onto a glass substrate bydipping coating and then oven dried at a temperature of 120° C. Finally,the dried substrate was subjected to 10% (vol) of H₂/Ar for 20 minutesto form a composite tungsten oxide film. The reduction temperature wasat 400° C. or 500° C., respectively.

An XRD spectrometer was used to analyze the structures of the tungstenoxide film formed with or without the catalyst. As shown in FIG. 9,after reacting at 300° C. for 20 minutes, the structure of the compositetungsten oxide film with the catalyst, transformed into a hexagonalstructure, which is the IR reflective structure. However, as shown inFIG. 10, the composite tungsten oxide film formed without the catalystdid not transform into the hexagonal structure even after reacting at atemperature of 400° C. or even 500° C.

EXAMPLE 9

5 g of ammonium metatungstate and 1.1 g of cesium carbonate was addedinto 40 mL of distilled water and thoroughly mixed. The pH value of themixture was adjusted to 12 by an NH₄OH aqueous solution. 0.4 wt % ofH₂PtCl₆.H₂O was added into the mixture to form a tungsten oxideprecursor solution. The tungsten oxide precursor solution was coatedonto a glass substrate by dipping coating and then oven dried at atemperature of 120° C. Finally, the dried substrate was subjected to 10%(vol) of H₂/Ar to form a composite tungsten oxide film. The reductioncondition was at a temperature of 260° C., 300° C., 400° C., or 500° C.,respectively, and the reaction time varied. After various reaction time(at a temperature of 260° C. or 300° C. for 240 min; at a temperature of400° C. or 500° C. for 60 min), the composite tungsten oxide film wasformed.

FIG. 11 illustrates the XRD spectrum of the composite tungsten oxidefilms at a best IR reflection mode at different reduction temperatures.As shown in FIG. 11, the lower reduction temperature requires the longerreduction time, and the higher reduction temperature requires theshorter reduction time.

Compared to the conventional tungsten oxide film which requiresreduction reaction to occur at a temperature of over 500° C., thereduction time and temperature of the disclosure may be adjusted duringthe formation of the tungsten oxide film. Moreover, the formed tungstenoxide film can have superior IR reflection. Thus, applicability of theheat shielding film is increased.

EXAMPLE 10

5 g of ammonium metatungstate and 1.1 g of cesium carbonate was addedinto 40 mL of distilled water and thoroughly mixed. 1 mol %, 3 mol %, 5mol %, or 10 mol % of the NH₄Cl was also added into the mixture,respectively. The pH value of the mixture was adjusted to 12 by an NH₄OHaqueous solution. 0.4 wt % of H₂PtCl₆.H₂O was added into the mixture toform a tungsten oxide precursor solution. The tungsten oxide precursorsolution was coated onto a glass substrate by dipping coating and thenoven dried at a temperature of 120° C. Finally, the dried substrate wassubjected to 10% (vol) of H₂/Ar at 400° C. for 60 minutes to form acomposite tungsten oxide film. A UV-VIS-IR was used to detect thetransparency and IR reflection of the composite tungsten oxide film.

FIG. 12 illustrates the IR reflection of the composite tungsten oxidefilm with halogen salt. As shown in FIG. 12, the composite tungstenoxide film with different amounts of halogen salt can still havesuperior IR reflection.

EXAMPLE 11

An ESCA (Electron Spectroscopy for Chemical Analysis) was used toanalyze the composition of the composite tungsten oxide film describedabove by a VS Scientific Microlab 310F. The detection depth was insideof 50 Å. The equipment was used to detect the amounts of the group VIIIBcatalyst which remained inside the composite tungsten oxide films formedin the examples. The result of ESCA was as followed: 21.22 mol % of W,63.48 mol % of O, 10.75 mol % of Cs, and 4.55 mol % of Pt, confirmingthe existence of the Pt catalyst in the composite tungsten oxide film.

EXAMPLE 12

5 g of ammonium metatungstate and 1.1 g of cesium carbonate was addedinto 40 mL of distilled water and thoroughly mixed. The pH value of themixture was adjusted to 12 by an NH₄OH aqueous solution. 0.4 wt % ofH₂PtCl₆.H₂O was added into the mixture to form a tungsten oxideprecursor solution. The tungsten oxide precursor solution was oven driedat a temperature of 13° C. Finally, the dried substrate was subjected to10% (vol) of H₂/Ar at 400° C. for 60 minutes to form a compositetungsten oxide film.

While the disclosure has been described by way of example and in termsof the preferred embodiments, it is to be understood that the disclosureis not limited to the disclosed embodiments. On the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

What is claimed is:
 1. A heat shielding material, comprising: (i)composite tungsten oxide doped with a group IA or IIA metal and halogen,represented by formula (II):M_(x)WO_(y)A_(z),   (II) wherein M refers to at least one of a group IAor IIA metal, W refers to tungsten, O refers to oxygen, and A refers toa halogen element, and 0<x≦1, 2.2≦y+z≦3, and 0<Z≦0.2; (ii) a group VIIIBmetal element; and (iii) a glass or a transparent polymer substrate,wherein the heat shielding material provides at least 50% reflectance atan IR wavelength of about 1400-2600 nm.
 2. The heat shielding materialas claimed in claim 1, wherein the heat shielding material ismanufactured by a method comprising: providing a tungsten oxideprecursor solution containing a group VIIIB metal element; coating thetungsten precursor solution on the glass or the transparent polymersubstrate; drying the tungsten oxide precursor solution to form a driedtungsten oxide precursor; and subjecting the dried tungsten oxideprecursor to a reducing gas at a temperature of 100° C. to 500° C. toform the composite tungsten oxide, wherein the tungsten oxide precursorsolution comprises (a) a tungsten oxide precursor, (b) a group IA or IIAmetal salt, (c) a group VIIIB metal, a group VIIIB metal oxide, a groupVIIIB metal salt, or a combination thereof, and (d) a halogen salt. 3.The heat shielding material as claimed in claim 1, wherein the heatshielding material is a film.
 4. A method for manufacturing a heatshielding material as claimed in claim 1, comprising: providing atungsten oxide precursor solution containing a group VIIIB metalelement; coating the tungsten precursor solution on a glass or atransparent polymer substrate; drying the tungsten oxide precursorsolution to form a dried tungsten oxide precursor; and subjecting thedried tungsten oxide precursor to a reducing gas at a temperature of100° C. to 500° C. to form a composite tungsten oxide.
 5. The method formanufacturing a heat shielding material as claimed in claim 4, whereinthe composite tungsten oxide is formed into a film.
 6. The method formanufacturing a heat shielding material as claimed in claim 4, whereinthe glass is a tempered glass.
 7. The method for manufacturing a heatshielding material as claimed in claim 4, wherein the step of subjectingthe dried tungsten oxide precursor to a reducing gas is at a temperatureof 250° C. to 500° C.
 8. The method for manufacturing a heat shieldingmaterial as claimed in claim 4, wherein the step of subjecting the driedtungsten oxide precursor to a reducing gas proceeds for about 20 to 240minutes.
 9. The method for manufacturing a heat shielding material asclaimed in claim 4, wherein the tungsten oxide precursor solutioncomprises (a) a tungsten oxide precursor, (b) a group IA or IIA metalsalt, (c) a halogen salt, and (d) a group VIIIB metal, a group VIIIBmetal oxide, a group VIIIB metal salt, or a combination thereof.
 10. Themethod for manufacturing a heat shielding material as claimed in claim9, wherein the tungsten oxide precursor comprises ammoniummetatungstate, ammonium orthotungstate, ammonium paratungstate, alkalimetal tungstate, tungstic acid, tungsten silicide, tungsten sulfide,tungsten oxychloride, tungsten alkoxide, tungsten hexachloride, tungstentetrachloride, tungsten bromide, tungsten fluoride, tungsten carbide,tungsten oxycarbide, or a combination thereof.
 11. The method formanufacturing a heat shielding material as claimed in claim 9, whereinthe group IA or IIA metal salt is represented by a formula of M_(p)N,wherein M is a group IA or IIA metal element comprising lithium (Li),sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), beryllium (Be),magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), or acombination thereof, and N is an anion or an anion group with negativevalence, and 0.5≦p≦12.
 12. The method for manufacturing a heat shieldingmaterial as claimed in claim 9, wherein the group IA or IIA metal saltcomprises group IA or IIA metal carbonate, group IA or IIA metalhydrogen carbonate, group IA or IIA metal nitrate, group IA or IIA metalnitrite, group IA or IIA metal hydroxide, group IA or IIA metal halide,group IA or IIA metal sulfate, group IA or IIA metal sulfite, or acombination thereof.
 13. The method for manufacturing a heat shieldingmaterial as claimed in claim 9, wherein the group VIIIB metal, the groupVIIIB metal oxide, or the group VIIIB metal salt comprises Pt, PtO₂,H₂PtCl₆.H₂O, H₂PtCl₆.6H₂O, N₂O₆Pt, PtCl₄, C₄H₆O₄Pt, Ni, NiO, Ni₂CO₃,C₄H₆O₄Ni.4H₂O, NiCl₂, H₈N₂NiO₈S₂.6H₂O, NiCl₂.6H₂O, NiF₂, NiBr₂,NiCl₆.6H₂O, Rh, Rh₂O₃, RhCl₃.H₂O, N₃O₉Rh, C₄H₉O₆Rh, Pd, PdO, H₂O₂Pd,N₂O₆Pd, PdBr₂, C₄H₆O₄Pd, PdCl₂, or a combination thereof.
 14. The methodfor manufacturing a heat shielding material as claimed in claim 9,wherein the halogen salt is represented by a formula of PA_(q), whereinA is a halogen element comprises fluorine (F), chlorine (Cl), bromine(Br), or iodine (I), and P is a cation or a cation group with positivevalence, and 1≦q≦12.
 15. The method for manufacturing a heat shieldingmaterial as claimed in claim 9, wherein the halogen salt comprisesammonium halide, alkylammonium salt, halocarbon, hydrogen halide,tungsten halide, benzene halide, halogenated aromatic, alkyl halide, ora combination thereof.
 16. The method for manufacturing a heat shieldingmaterial as claimed in claim 4, wherein a pH value of the tungsten oxideprecursor solution is over
 7. 17. The method for manufacturing a heatshielding material as claimed in claim 4, wherein the reducing gas ishydrogen.